The present invention relates to a throttle valve for hydraulically or pneumatically operated tools, comprising a valve housing which receives a throttle part and is arranged between a tool and a power fluid line, a first and a second apparatus being arranged to be in operative connection with the valve housing, the second apparatus being arranged to be actuatable to regulate the drive only after an intentional actuation of the first apparatus to prevent inadvertent or unauthorized actuation.
Hydraulically or pneumatically operated tools can be used on a remote construction site independently of an electrical power supply. The hydraulically or pneumatically operated tools are notable here for a compact structure and the high power that can be fed to the drive. Throttle valves are used to allow regulation of the energy supply to the drive. However, the high power fed to the tool can represent a substantial risk for the operator, especially in the event of inadvertent or unauthorized actuation. Consequently, safety devices for hydraulically or pneumatically operated tools are necessary.
U.S. Pat. No. 4,444,091 has disclosed a pneumatic valve with throttle capability and with a device for preventing inadvertent or unauthorized actuation. In a valve housing, arranged concentrically with one another from inside to outside, are a valve pin, a tubular shut-off part, a hollow cylinder closed at one end and an air volume control device. These parts of the arrangement are moved, in the normal case, in two mutually opposite directions perpendicular to the main axis of the valve housing. These movements take place against the spring force of two springs. Arranged at the end of the valve pin are detent balls which, as a result of the conically extending inside surface of the hollow cylinder, can bring about a coupling of the movement of the valve pin with the movement of the shut-off part. The air feed to a compressed air-operated motor is enabled only when the hollow cylinder and the valve pin have been actuated in two mutually opposite directions in succession. The valve pin is actuated by a lever on one side of the housing and the hollow cylinder has to be actuated from the opposite side of the housing. The maximum air volume allowed through can be set by rotating the hollow cylinder by means of a screwdriver. Substantially, the valve allows not continuous adjustment but only a settable open/shut adjustment. The apparatus for preventing inadvertent or unauthorized actuation is accessible and capable of operation only in two precisely defined areas of the valve housing.
On the basis of this prior art, it is an object of the invention to provide a throttle valve for hydraulically or pneumatically operated tools which is constructed from as few parts as possible and which, independently of its position of installation relative to the tool, can be operated by the operator in any position safely, without risk of injury and in accordance with correct ergonomic principles.
The foregoing object is achieved by a throttle valve for hydraulically or pneumatically operated tools, comprising a valve housing which receives a throttle part and is arranged between the tool and the power fluid line, a first and a second apparatus being arranged to be in operative connection with the valve housing, the second apparatus being arranged to be actuatable to regulate the drive only after an intentional actuation of the first apparatus to prevent inadvertent or unauthorized actuation, the first apparatus having at least a first release mechanism for initial unlocking and a second release mechanism for further unlocking, the release mechanisms being movable in two directions (x, y) extending perpendicularly to one another, and the second apparatus for regulating the drive being arranged to be movable in a direction of rotation (z) extending around the x direction.
It is advantageous that at least the first apparatus for preventing inadvertent or unauthorized actuation can be simply and safely operated by the operator in any position. This is achieved in that the first release mechanism is designed as a release ring, which is arranged to be movable in the direction of the housing axis by displacement towards the valve housing. This is also achieved in that the second release mechanism is designed as a latch having a free end and arranged to be movable in a direction perpendicular to the housing axis. Moreover, this is additionally achieved in that the release ring has a projection oriented radially to the housing axis which engages against the spring force of a conical wire spring in an annular seating on the valve housing so that the release ring is arranged to be movable resiliently in the direction of the housing axis for unlocking the second release mechanism.
It is also advantageous that the drive of the hydraulically or pneumatically operated tool can be simply and precisely adjusted. This is achieved in that the second apparatus is designed as a rotating sleeve which is arranged to be movable in the direction of rotation around the housing axis in operative connection with the valve housing. This is also achieved in that the rotating sleeve for controlling the drive is connected to a control pin which interacts with a control ramp on the throttle part in such a way that the rotational movement of the rotating sleeve about the housing axis moves the throttle part in the direction of the housing axis and regulates the fluid feed from the fluid line for the hydraulic or pneumatic drive of the tool.
It is further advantageous that the risk of injury for the operator in operating the hydraulically or pneumatically operated tools is prevented. This is achieved in that a detent is arranged in the release ring and interacts with the freely movable end of the latch for unlocking in such a way that the latch can only be moved after an intentional actuation of the release ring against the spring force of the conical wire spring in a direction perpendicular to the housing axis.